<html lang="zh-cmn-Hans">

<head>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="/bootstrap-4.0.0-dist/css/bootstrap.min.css">
    <style>
        .my-container {
            width: 300px;
            height: 200px;
            background: #ddd;
            margin-bottom: 5px;
        }
    </style>
    <title>元素size变更</title>
</head>

<body>
    <div class="my-container">
        <div class="bg-primary w-50 h-50">小马视频</div>
    </div>
    <div class="my-container">
        <div class="bg-success w-75 h-100">小马视频</div>
    </div>
    <!-- Optional JavaScript -->
    <!-- jQuery first, then Popper.js, then Bootstrap JS -->
    <script src="/bootstrap-4.0.0-dist/others/jquery-3.2.1.slim.min.js"></script>
    <script src="/bootstrap-4.0.0-dist/others/popper-1.12.9.min.js"></script>
    <script src="/bootstrap-4.0.0-dist/js/bootstrap.min.js"></script>
</body>

</html>